On mine, I noticed that with belt off, the clutch flywheel turned/spun rather freely, but you could hear obvious dry bearing noise. Sounded like bricks being rubbed together. That's if system is out of commission anyway. Some manuals, like Helm's, have detailed diagnostics which can walk you through electric testing of all that's needed to test. I knew that my belt had burned off, heard the dry bearings, and would have needed to replace SOMETHING, so during removal of compressor/clutch assy., I removed clutch and saw obvious meltdown of clutch assy. All I had to do then was replace clutch, and hope that was it. That was it. If nothing's moving, and you're sure your system is charged, then electronic diagnostics is prob. where you would want to start. After I replaced clutch, before charging, it spun freely by hand, and as quiet as ever with it's sealed bearings in good shape. Good luck. Check Ebay for info on Helm's for your specific model car. You'll be surprised.